This invention is directed to thermosensitive recording materials for use in facsimile, thermal printer, hot-pen recording systems and the like. More particularly, it relates to a low cost thermosensitive recording material which has a high sensitivity and high image quality.
Recording materials containing an electron donating dye precursor and an electron accepting compound are well known as materials for use in such applications as pressure sensitive recording paper, thermosensitive recording paper, photo- and thermosensitive recording paper, electrothermosensitive recording paper and the like. Such applications are disclosed in detail for example in British Patent 2,140,499, U.S. Pat. No. 4,480,052, U.S. Pat. No. 4,436,920, JP-B-60-23922, (the term "JP-B" as used herein means an "examined Japanese patent publication"), JP-A-57-179836 (the term "JP-A" as used herein means an "unexamined publication Japanese patent application"), JP-A-60-123556 and JP-A-60-123557.
Because of the advance in the development of high speed, low energy recording instruments triggered by the recently expanding use of thermosensitive recording materials in various fields, there is a great demand for a thermosensitive recording material which possesses a high sensitivity and a high image quality, but has a low capacity to adhere stains to a thermal head. To satisfy these demands, various techniques have been proposed such as a process in which an undercoat layer is inserted between a support and a thermosensitive recording layer and, as disclosed in JP-A-2-1369, a process in which components of a coating solution and their contents and the like are specified. These prior art processes, however, do not show satisfactory results. The production cost of a thermosensitive recording material greatly depends on its support material. A material having a low Steckigt sizing degree of 10 seconds or below may be useful as a low cost support. Such a support, however, is apt to cause deterioration of the surface conditions of an undercoat layer, especially when a blade coater is used, and therefore to cause the problem of decreasing sensitivity and image quality of the resulting thermosensitive recording material.